Electric hammer with rectifier in handle



Oct. 7, 1952 c s WEYANDT I 2,613,241

ELECTRIC HAMMER WITH RECTIFIER IN HANDLE Filed Sept. 19, 1949 2 SHEETS-SHEET 1 25 2 J4 MI I 39 O J5 35. J7 55 0 J6 56 /l\ 5'2 0 w u w Q 41 Q542 Q4 41 Z1 "f; \ii\ 26 V J 2J- 0 O H 15 IN V EN TOR. Cor/6. h/eyandzfiOct. 7, 1952 c s, WEYANDT 2,613,241

ELECTRIC HAMMER WITH RECTIFIER IN HANDLE Filed Sept. 19, 1949 2SHEETSSHEET 2 gig-h1g2 INVENTOR. COr/Jh/gano.

56 Y Azrm/f/ Patented Oct. 7, 1952 ELECTRIC HAMMER WITH mammal;

HANDLE:

Carl s. Weya'ndt, Homer city-P Application September 19, 1949, SerialNo. 116,509

This invention relates generally to electromagnetic reciprocatinghammers and more particularly to an electric hammer having spacedelectromagnetic coils energized by alternate electricimpulses usuallyobtained from a rectified half wave alternating current circuit.

Electric hammers have been constructed to operate from various types ofrectifiers such as vacuum tube diodes or dry disc rectifiers. Theserectifiers, heretofore, have been mounted in a separate housin spacedsome distance from the hammer itself, generally to feet. Onedisadvantage of such construction is that a separate unit for therectifier is required, making it awkward to handle in many operationssuch for instance as drilling in ceilings overhead and drilling high onside walls of buildings Another disadvantage is that in'groundingff's'uch devicesit is necessary to run a ground wire from thehammer to the case of the rectifier and from the case of the rectifierto the ground connection; 'This requires the use of four wires fromtherec'tifier to the hammer and four point recep'tacles and plugs. Italso requires three wires fromthe rectifier to the source of supply andthe ground. The requirement of four wires from the rectifier to thehammer ismore expensive than the ordinary three-wire or two-wire cableand does not give as good service as the lesser wired cables since thereis more danger of breakage internally in the cable, due to twisting andbending in normal use. Another disadvantage is that in order to breakall live connections to the hammer coils, it is necessary to have athreepo'le switch. This is rather an expensive device and means that thehandle to contain the switch must be larger, making the device moreclumsy and heavier and more difiicultto handle as a portable tool.

These objections have been eliminated in the present invention byplacing the rectifier within a portion of the hammer itself. This makespossible the use of a two-pole switch to completely disconnect any liveconductors from the hammer. It makes possible the use of a standardthreeconductor cable from the source of supply directly tothe hammer forboth supplying power and grounding of the hammer.

One object of this invention is the provision of an electro'magneticallyoperated reciprocating hammer having its rectifier built within thehandle to provide a three-conductor cable with two" conductors for thesupply circuit and one independent conductor for grounding the casing ofthe hammer.-

eating hammer with the plane of the discs paral- 4 Claims. (01.172-126)lel; with the vibratory action of the hammer {to avoidvmechanicaifixture of the discs. Another objectis the provision of'anelectro: magnetic reciprocating'hammer havingan 1minterruptedfgroundconnection to the casing and a doublepole switch in'the operatingcircuit of the hammer... I a

Another object is the provision of a dry disc rectifier built withinthe-handle of an electromagnetic hammer and requiring less,v discs pervolt owing to the proximity and the'inductive reactance of the hammeroperating coils. I Another object is theprovision of a rectifiermounting that supports one end of the cable and forms a portion of thehandle. a a I Other objects and advantages appear in the followingdescription and claims' The accompanying drawings show, for.the purposeofexemplification without limiting the in: vention or claims theretogcertaincpracticalflem bodiments of theinvention wherein: a

Fig. 1 is a sectional view of the electromagnetic reciprocating hammer;Fig. 2 is a circuit diagram of the amme'r shown i'nEFig. 1; and Fig. 3is a view in side elevation electric hammer. Y v

Referring principally to the drawings, the electric hammercomprises thecylindricalfhou'sing I having a nose casting 2fitted to the bottomthereof and a'handle casting 3 fitted to thetopthereof. Anelectromagnetic core 4 is constructedonjthe tube '5 made of nonmagneticmaterial such as brass, bronze or other suitable alloy. The bore of thebarrel 5 is cylindrical andits outer surface is octagonal to receive theeight sides of the electromagnetic core 4 which is brazed thereto toform an integral structure with annular winding recesses to receive thecoils 6 and 1. A piston 8 of electromagnetic material is substantiallythe same diameter as the bore of the cylinder Sand reciprocatesthereinand is arranged to strike; the tool shank 9 adjacentthe lower endyof thehammer and the resilient stop l0 withthe'upperen'd ofthe handle; a

-' The resilient stop l0 comprises an'elastomer member I I having acylindrical portion 12 fitting within-the bore? l3 of the handlecastings and a smallercylindrical portion l4 extending into the upperbore of the tubular barrel 5. The elastomer "member H has an openingthere- -through to exhaust the air from the bore'of the barrel 5 aheadof the piston 8 which strikeslthe elastomermember l0. 'A pair of tierodbolts" l5 pass through theleaf spring l6 adjacent the ends thereof andare secured by means of'thenuts and spring washers as shown." The lowerend of the tierods l5 are attached to the nose casting-Z showingthe toconnect it with the handle casting 3 and hold them both in assembledrelation on the cylindrical housing I of the hammer.

The elastomer member ll, having its small diameter portion l4 and itslarge diameter portion [2, is arranged to aid the spring 16 in stoppingthe upward travel of the free piston 8, striking and deforming theelastomer member ll,

both of which absorb energy from the blow and return it to the piston asit is energizedv by, the lower coil 1 on its downward stroke. tomermember H provides a novel mode for receiving the shock andretransmitting it to the free piston.

The handle casting 3 is provided with a hous- The elas-I ing which isenlarged, as shown at 2| in Figs. 1

inthehorizontal plane when the hammer is held in a vertical position,the rectifier discs are disposed parallel to the. axes of'the piston andany shocker vibration due to the axial movement of the free piston}; isnot transmitted to the rectifier discs in the direction that would tendto flex them, but is parallel to-the discs. This aids in obtaining along life-for the rectifier;

The housing 2| is provided with a series of openings through which airmay; pass to cool the-discs of the rectifier.

As shown in Fig; 1, the three wire conductor 31 extends throughthereinforcing member 32 to the interior of the handle, from whence thethree wires33, 34 and 35'extend. The wire 33 will be noted to befastened by a bolt to the interior of the lid 22 that is in turn securedto the housing ofthe hammer to ground the frame. I

1 The wires 34. and 35 are connected to'the ter- 'minal block 36jand.extend to the switch 3T'which isafdouble pole switch, thereby openingboth sides of the circuit to the hammer. The wire 34,, which representsone side of the A. 0. line; extends through the switch3lv and isconnected by..con-

(motor 38to the center. of the rectifie'ristack as indicated at 39. theswitch 31; is connected by the conductor 40 topon'e end of .both .coil's6 and], as shown in Fig. 2. The other end ofcoil 6 is connectedby thewire 4| to one end of the rectifier. stack, as indicated,atj42.' The.other end of. the coil 1 is connected bythefwire 43 to the other-lendofthe rectifier stack,.as.indicated at 44.; Thus, the twopole. switch31Ibr'e'aks both the lines/to; theoper- The wire 35 passing' throughating'mechanism of the hammer and the: ground wire 33-is maintained atall timesetdthe casing o f-the tool. 'Sucha simple circuit could not beobtained unless "the rectifier is formed'as .aunitary part oftheelectrichammer as shown.

-, ;The impedance of "the hammer operating coils 6 and 7 is high due tothe constantly varying reluctance uponthe reciprocation of the core:8.Ordinarily it would require. twelvev rectifier discs for 110 v. cyclecurrent. However the high varying reluctance of the coils' reducesthe.discs to four per coil, thus permitting'such a small quantity to'beassembled asra unitformingan integral-part of the hammer-- I claim:

1. An electric hammer comprising a housing, a free piston of magneticmaterial reciprocable in said housing, spaced coils carried by saidhousing to.electromagnetically actuate the free piston and having theiradjacent ends connected together, a unidirectionally assembled rectifierstack and switch means for opening the line current mounted on saidhousing, a tri-conductor current supply cable having one conductor forground connected to said housing and the other two conductors to supplyalternating current to said switch means, conductors from the two poleson the other side of said switch to the center of ,the rectifier stackand the common coil connection respectively; and conductors between theother ends of said coils and the ends of. the rectifier stack.respectively thereby eliminating external control and reducing theexternal connections to the primary power supply;

2. .An integral handle casting for an electromagnetic reciprocatinghammer consisting of a transverse handgrip having spaced. therefromeanannular reciprocating motor housing, an integral wall on one endof thehandgrip extending to said housing and annularly shaped to form achamber open on one end thereof, a disc rectifier having mounting meansengageable with the wallof the chamber tosupport the rectifier inthelchamber with the discs lying parallelwith. theaxis of, thereciprocating motor housing, anda closuremember for said chamber.

3. An integral handle casting for an electromagnetic: reciprocatinghammer consisting. of a transverse handgrip having spaced therefrom anannular reciprocating motor housing, an integral wallonone end of thehandgrip extending to said housing and annularly shapedto form a chamberopen on one end/thereof, a discrectifier have ing mounting meansengageable with, the walls of the chamberto support the rectifierin thechamber with the discs lying parallel with the axis of, thereciprocatingmotor housing, a closure member for said chamber, and a flexibleelectric cable supported by. saidclosure member as supplying. electriccurrent to said. hammer.

4.. .An. integral handle casting for. an. electromagnetic reciprocatinghammer consisting of a transverse handgrip having spaced therefromacircular housing for receiving a reciprocating motorganintegralwall.onone end of thehandgrip extending: to said housing and annularly shapedto, form. a chamber open at one .end thereoiflja closure member for saidchamber, a discrectifler having a mounting bolt engageable withs'aidcl'osure, member. of the chamber to support the rectifier in saidchamber with its discs axially of the. cylindrica1 housing, and.parallel with the reciprocating. movement of the hammer.

CARL s. .WEYANDT;

REFERENCES CITED The following-references are of record in the file ofthis patentz UNIIEDTSTATES PATENTS Number Name Date-p 1,827,372 Riddel-la :.'Oct.l3, 1931 1,899,741 1 Bauer; ;Eeb. 28, 1933 2,100,660 GreinerNov; 30,193! 2,154,627 Knobel --Apr. 18, 1939 2,310,166 Way, Feb. 2,.1943 2,403,034 I Weyandt et al. July 2, 1946 2,497,141 Schultz Feb.14.1950

